The invention relates to a fluorescence diagnostic apparatus which conducts spectrometry on fluorescence emitted from a living tissue of a patient and diagnoses whether a tumor site exists or not.
It is known that, when a living tissue is irradiated with light of a wavelength of 420 to 480 nm (excited light), an intrinsic substance (for example, NADH and FMN) of the living tissue is excited to emit fluorescence. Furthermore, it has been revealed that fluorescence emitted from a normal site of a living tissue is different in spectrum from that emitted from a tumor site. Specifically, as shown in FIG. 9, fluorescence emitted from a normal site of a living tissue has a spectrum in which the green region is considerably stronger than the red region, and fluorescence emitted from a tumor site of a living tissue has a spectrum in which the red and green regions are slightly different in intensity from each other. Conventionally, a fluorescence diagnostic apparatus using this phenomenon has been proposed. In the apparatus, fluorescence is guided by a light receiving probe to the outside of a living body, the spectrum of the fluorescence is measured by a spectroscope disposed outside the living body, and a diagnosis on whether a tumor exists in the living body or not is conducted.
FIG. 10 is a diagram showing the configuration of a part of such a fluorescence diagnostic apparatus. Referring to FIG. 10, a light guide 102 of an endoscope 101 irradiates a living tissue O to be diagnosed, with excited light which is introduced from a light source (not shown) that is connected to the basal end of the light guide. The surface of the living tissue O which is irradiated with the light is observed by the operator via an image guide 103 of the endoscope 101. A light receiving probe 100 which is connected to a spectroscope (not shown) disposed outside the living body is guided to the living tissue O which is to be diagnosed, through a forceps channel of the endoscope 101. The light receiving probe 100 conveys fluorescence produced from a site (the living tissue O) which is in front of the probe, to the spectroscope (not shown). The operator adjusts the direction of the tip end portion of the endoscope 101, while observing the living tissue O to be diagnosed via the image guide 103 of the endoscope 101, thereby directing the light receiving probe 100 to each site of the living tissue O. The site to which the light receiving probe 100 is directed is diagnosed whether it is normal or not, based on the spectrum measured by the spectroscope which is not shown.
In the thus configured fluorescence diagnostic apparatus of the prior art, however, movement of the light receiving probe 100 with respect to the endoscope 101 (movement in a direction perpendicular to the center axis of the endoscope 101) cannot be conducted. In order to move the light receiving probe 100, therefore, the tip end of the endoscope must be operated so as to be bent. During the operation of bending the tip end of the endoscope, the range which is to be observed via the image guide 103 is moved. Therefore, the operation of directing the tip end of the light receiving probe 100 to a desired site is very cumbersome and requires the operator to have a high skill. Furthermore, it is difficult to move the tip end of the light receiving probe 100 so as to follow the motion of the diagnostic site during a diagnosis, and hence the tip end of the light receiving probe 100 is frequently positionally misaligned with the diagnostic site. As a result, a diagnosis focused only on a specific diagnostic site is made difficult to do, and the reliability of the diagnosis is lowered.